Problems with Lunotriquetral Fusion

77 Problems with Lunotriquetral Fusion

Rocco Barbieri

77.1 Patient History Leading to the Specific Problem

A 23-year-old man presents with persistent dorsal ulnar pain on his dominant right wrist following a surgical procedure to fuse the lunate and triquetral bones 1 year earlier. According to the patient, the procedure was performed to relieve pain that was the result of the joint between his two bones being abnormally formed from birth. The patient had been a collegiate basketball player and during the last 2 years of his career, he had developed persistent ulnar-sided wrist pain. Since the procedure, he has also had limited motion as well as severe hypersensitivity and diminished sensation along the dorsal ulnar border of the hand. He was referred to the office by an outside orthopaedist with a diagnosis of a failed lunotriquetral arthrodesis.

77.2 Anatomic Description of the Patient’s Current Status

77.2.1 General Appearance

The patient has a well-healed longitudinal 4-cm incision on the dorsal aspect of the wrist in the axis of the ring digit. The wrist is moderately swollen and is exquisitely tender along the lunotriquetral joint. He has very minimal tenderness in the region of the ulnar fovea and has no tenderness along the distal radioulnar joint, the scapholunate interval, or the anatomic snuff-box. He has severe pain with lunotriquetral ballottement and compression tests. The patient also has hyperesthesia and diminished sensation to light touch along the dorsal ulnar border of the hand. He has Tinel’s sign 1 cm lateral to the incision along the path of the dorsal sensory ulnar nerve. There are no tropic changes along the skin and the patient has full range of motion of the digits. His wrist range of motion is limited to 25 degrees of flexion and 30 degrees of extension with 5 degrees of radial deviation and 10 degrees of ulnar deviation. He exhibits pain at the end range of wrist motion. Pronation and supination are normal and nonpainful. He has pain with ulnar impaction maneuvers.

77.2.2 Radiographs

The patient presented with a disk that contains his prearthrodesis radiographic studies. These include plain films (Fig. 77.1a) that demonstrate an irregularity along the lunotriquetral joint. A three-phase bone scan confirms the presence of increased uptake in the lunotriquetral region of the wrist (Fig. 77.1b). An MRI of the wrist reveals the presence of a Minnaar type I lunotriquetral coalition (Fig. 77.1c). Review of the patient’s operative report explains that the arthrodesis was done using artificial bone graft and K-wire fixation through a dorsal approach. X-rays from the first postoperative visit demonstrate two 1.1 mm guide wires transfixing the lunotriquetral joint (Fig. 77.2a). New X-rays taken at the time of this visit reveal the presence of a failed arthrodesis of the lunotriquetral joint (Fig. 77.2b).

77.3 Recommended Solution to the Problem

A complete review of the patient’s complaints and presurgical studies confirms the fact that the patient underwent a lunotriquetral arthrodesis in order to treat a symptomatic partial carpal coalition. The indications and the decision to proceed with an isolated lunotriquetral fusion were correct. The primary problem is likely due to the surgical technique. K-wire stabilization across an intercarpal fusion provides no compression and little stability compared to compression screw fixation. In addition, the use of synthetic bone graft may have made the likelihood of failure higher than if autograft had been utilized. Finally, it seems that the surgical approach, including the placement of the K-wires, either damaged or scarred the dorsal sensory branch of the ulnar nerve. The nerve typically crosses dorsally to innervate the dorsal ulnar portion of the wrist emerging from the dorsomedial border of the flexor carpi ulnaris at a mean distance of 5 cm from the proximal edge of the pisiform. Great care should be taken not to injure the nerve when performing surgical approaches in this region. Revision of the failed lunotriquetral arthrodesis should address all of the shortcomings of the original procedure. A careful surgical approach with exploration of the dorsal sensory branch of the ulnar nerve should be carried out, followed by a dorsal approach to the lunotriquetral joint. Clearing out of the fibrous tissue on the nonunion site with exposure down to bleeding bone surfaces on the lunotriquetral joint needs to be accomplished. Cancellous bone graft should be harvested from the patient and placed in the arthrodesis site, followed by headless compression screw fixation from the triquetrum to the lunate. The wrist should be immobilized for 8 weeks, followed by splinting and protected range of motion for an additional 4 weeks.

77.3.1 Recommended Solution to the Problem

The dorsal sensory branch of the ulnar nerve needs to be explored during the repeat surgical approach to the lunotriquetral joint.

The nonunion site needs to be debrided down to healthy, bleeding cancellous bone.

Cancellous autograft should be placed in the arthrodesis site.

Compression screw fixation is used to stabilize the fusion.

Immobilization for 8 weeks, followed by protected range of motion in a splint for an additional 4 weeks is recommended.

77.4 Technique

The patient is taken to the operating room and placed in the supine position with the arm abducted 90 degrees on a radiolucent arm board. General anesthetic supplemented by a regional block is optimal for postoperative pain control. A well-padded tourniquet is applied above the elbow and the limb is prepped and draped in the usual sterile manner. The limb is exsanguinated using an Esmarch tourniquet and the tourniquet is elevated to 250 mm Hg. The previously utilized dorsal incision is employed extending it proximally for 1 to 2 cm into an unscarred area. Radial and ulnar flaps are elevated and the proximal portion of the dorsal sensory ulnar nerve is identified proximally. Using meticulous dissection under loupe magnification, the dorsal sensory branch of the ulnar nerve is carefully released from the surrounding scar tissue and in this case it was found to be in continuity but trapped within the scar at the site of the previous K-wire insertion sites. After freeing up the nerve, the interval between the fourth and the fifth dorsal compartments is determined and the extensor tendons are lifted up away from the underlying dorsal capsule of the wrist. The extensor retinaculum does not need to be released for this maneuver. Next, a Weitlaner retractor is used to spread the extensor tendons away from the dorsal wrist capsule. The dorsal radiotriquetral and scaphotriquetral ligaments are identified and a capsulotomy is made as described by Berger and Bishop (Fig. 77.3). In this manner, the lunotriquetral joint is exposed and the radiocarpal and midcarpal joints are examined for the presence of any arthritic changes other than the lunotriquetral joint. C-arm fluoroscopy can be utilized to help localize landmarks during the dorsal approach.

At this point, two 1.5-mm K-wires are drilled in a dorsal-to-palmar direction in the lunate and triquetral bones in order to rotate and distract them. A combination of a curette and a rongeur is used to remove all fibrous tissues and denude any remaining cartilage down to bleeding subchondral bone on both sides of the lunotriquetral joint. Usually, the volar 15% of the joint is not removed in order to maintain the proper anatomic relationship between the lunate and the triquetrum.

Next, a guidewire for a headless screw is placed across the joint starting from the ulnar border of the triquetrum to the center portion of the lunate perpendicular to the lunotriquetral joint. Using the previously placed 1.5-mm wire, the lunate is rotated to a neutral position in its relationship to the distal radius when placing this wire. A second wire is passed to help control rotation when the headless screw is inserted.

At this time, the length of the screw is measure based on the guidewire depth and usually 4 mm is subtracted from this number to allow for appropriate countersinking of the headless screw. Before inserting the compression screw, cancellous bone graft is harvested to fill the lunotriquetral joint. Typically, olecranon bone graft from the ipsilateral arm is harvested by making a 2-cm incision along the radial crest of the olecranon and with electrocautery elevating the periosteum off the bone (Fig. 77.4). Handheld techniques can be used to make a cortical window in the olecranon and harvest cancellous bone. It is more efficient to use the Acumed bone graft harvesting drill to accomplish this task (Fig. 77.5). Usually 2.5 to 3 cm of cancellous bone can be harvested from the olecranon. Alternatively, a similar quantity of cancellous bone can be obtained from the distal radius through either a volar or a dorsal approach.

Dec 2, 2021 | Posted by in PHYSICAL MEDICINE & REHABILITATION | Comments Off on Problems with Lunotriquetral Fusion

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